Revert 234734 "Allowing file:/// in Instant Extended's Most Visi..."

That CL broke logging which Most Visited tiles were clicked since the <a ping="..."> param is now being ignored. Please contact me before you work on a CL to put that back into place, since there are plans to rely on that ping parameter for other purposes.

> Allowing file:/// in Instant Extended's Most Visited links.
> 
> BUG=306137
> 
> Review URL: https://codereview.chromium.org/36073011

TBR=pedrosimonetti@chromium.org

Review URL: https://codereview.chromium.org/93003003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237637 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237637